Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal cancer with an average 5 year survival rate of <6%, since most patients present with local or distal metastasis at the time of diagnosis when curative treatment options are extremely limited. Asymptomatic pancreatic cysts detected in more than 2% of the general patient population with abdominal imaging presents a unique opportunity for developing early detection biomarkers of PDAC since mucin-secreting pancreatic cysts, such as the more frequently detected intraductal papillary mucinous neoplasms (IPMNs) and the less frequent mucinous cystic neoplasms (MCNs) are bona fide precursor lesions of PDAC. Furthermore, biomarkers of invasive cancer from mucinous cystic lesions is expected to address the critical unmet clinical need of reliably distinguishing indolent from aggressive cystic lesions to help patients with indolent disease avoid the risk of surgery associated morbidity and mortality. In a recent limited sample size cohort study, we identified by NextGen sequencing (NGS) differentially abundant cyst fluid miRs (cf-miR) from patients with high grade IPMN-invasive pancreatic cancer compared with those with low grade IPMN demonstrating the feasibility of developing cf-miR signatures as early detection biomarkers for stratifying high risk IPMN predisposed to progress to invasive PDAC from low risk indolent cysts (Wang et al. Cancer Letters 2015; 356: 404-409). In this project, we are proposing to undertake detailed analyses of NGS derived cyst fluid miRNome (cf-miR) from IPMN patients with benign or low grade dysplasia and those with high grade dysplasia- invasive cancer to develop cf-miR signature that can differentiate aggressive IPMN from benign and indolent lesions. Additionally, we propose to investigate extent of overlap between the cf-miR and the plasma miR signatures from IPMN patients associated with PDAC. The study will take advantage of diagnostic cystic sampling with endoscopic ultrasound (EUS) for IPMN diagnosis and IPMN related histological tissue and bio-specimen banking at the Helen Diller Family Comprehensive Cancer Center at UCSF by my collaborators, Dr. Kimberly Kirkwood and Dr. Pamela Paris respectively (Please see the letters attached). We propose the following specific aims: Aim 1: Develop cf-miRNA biomarker signature for IPMN risk stratification utilizing NGS and qRT-PCR. Aim 2: Investigate functional significance of the differentially abundant cf-miRs in resected tissue samples and in an in vitro cell line model of mutant K-RasG12V expressing non-tumorigenic human pancreatic ductal epithelial (HPDE) cells. Aim 3: Evaluate cf-miRNA biomarker signatures in blood plasma from patients with pancreatic cysts.